Uni-Filter Junior. Specification: Filtration Efficiency. Bacterial: 99.99999%. Viral: 99.999 %. Dead space: 35 ml. Pressure Drop: at 30 l/min: 0.05 kPa/0.5cm H2O, at 60 l/min: 0.12 kPa/1.2 cm H2O. Weight: 16 g. Connections: Patient side: 15 F/ 22 M, Machine side: 15 M/ 22 F. Materials: Housing: Polypropylene, Filter Material: Polypropylene and acrylic fibers. Note: Recommended changing frequency: After a maximum of 24 hours of use or sooner if there is evidence of humidity inside of the filter. Unit of Measure: pkg of 50 pcs.